Research On Robust Sliding Mode Control Of Cyber-physical Systems Under Periodic DoS Attack

With the advancement of industrialization,today’s society is entering a new era of intelligence,digitalization and "Internet of Everything".The traditional industrial control systems have been upgraded and transformed by integrating computing,control and communication technologies,which promotes the emergence of Cyber-Physical Systems(CPSs).Information transmission is the most basic function in CPSs,and the information transmission channel is vulnerable to various types of network attacks in the information space,which can cause information transmission errors,delays or interruptions,thus affecting the dynamic performance of control and even destabilizing the system.Denial-ofService(Do S)attacks have become one of the most representative malicious network attacks due to their deceptive nature,low cost and easy implementation.Therefore,it is of important theoretical value and practical significance to study the security control problem of CPSs under periodic Do S attacks.From the perspective of robust stabilization and combined with sliding mode control method,this thesis studies the CPSs security control under periodic Do S attacks.The main work and achievements of this thesis are as follows:(1)The security control problem of CPSs with uncertain parameters under periodic Do S attacks is considered,and a static output feedback control method is used to ensure stable system operation.Firstly,by constructing Lyapunov functions,giving linear matrix inequality conditions to solve the sliding mode surface parameters.Secondly,by combining the periodic Do S attack parameters and the event-triggering mechanism to design the static output feedback sliding mode controller.Then,according to periodic Do S parameters and sliding mode controller parameters combined with event-triggering mechanism,sufficient conditions for ensuring the accessibility of sliding mode surfaces are given to achieve the closed-loop stability of the system.Finally,the effectiveness and superiority of the control method are verified by simulation.(2)Based on the work(1),an event-triggered sliding mode control algorithm which combined state observer with sliding mode control method for the case of external disturbances and unobservable internal states of the system is proposed.Firstly,the state observer is used to estimate the state in real time,and the event-triggered sliding mode controller is constructed from the state estimates.Secondly,a linear matrix inequality condition is given to solve for the parametric design of the sliding mode surface.Then,a sufficient condition is proposed to guarantee the closed-loop stability of the system under periodic Do S attack and to make the system trajectory converge within the desired sliding mode boundary.Finally,the efficiency of the control algorithm is verified by simulation.(3)Based on the study in work(2),the quantization control method is introduced to save communication resources and reduce the communication load.First,the sliding mode controller is designed by uniting the periodic Do S attack parameters,linear sliding mode surface parameters,event-triggering mechanism and quantization mechanism.Secondly,sufficient condition which based on the parameter of periodic Do S attack and controller is given to guarantee the reachability of the sliding mode surface and achieve closed-loop stability of the system,periodic Do S attack and perturbation parameters.Then,the sufficient conditions for the quantizer to capture the system state in one step are proposed to avoid quantization saturation.Finally,the effectiveness and superiority of the control algorithm are verified by simulation.